US Patent 7021005 Gate operator

A gate operator in a first configuration opens and closes a gate that swings about an upstanding pivotal axis. In a second configuration the gate operator opens and closes a gate that extends and retracts along a straight line. A motor-driven wheel extends from the bottom of an open-bottomed enclosure and is perpendicular to the gate in the first configuration and parallel to the gate in the second configuration. The wheel is driven by a reversible DC motor. Turning a jack screw in a first direction increases the bias on an adjustable compression spring so that the weight of the gate is transferred to the wheel and rotation of the jack screw in an opposite direction shifts weight from the wheel to the gate.